By Cindy Wooden | Catholic News Service

VATICAN CITY -- A Christian's faith must be visible in the way that person lives, treats those around him or her and interacts with the environment, Pope Francis told visitors from the World Communion of Reformed Churches.

"Faith cannot be shared if it is practiced apart from life, in unreal isolation and in self-referential communities resistant to change," the pope said June 10 during a meeting with the leadership team of the communion, an umbrella organization for Congregational, Presbyterian, Reformed, United, Uniting and Waldensian churches around the world.

"Our faith in Jesus impels us to live charity through concrete gestures capable of affecting our way of life, our relationships and the world around us," Pope Francis said.

The Rev. Jerry Pillay, president of the communion and a minister of the Uniting Presbyterian Church in South Africa, told reporters the organization is promoting activities around the theme, "called to communion, committed to justice."

With Pope Francis, he said, "I think we are in a new place" in the ecumenical dialogue. "We are sensing a great, great opportunity and invitation to dialogue," both on theological issues, but also in how Christians can work together to be witnesses of Christ and Christian values in the world.

The Rev. Chris Ferguson, general secretary of the communion and a minister of the United Church of Canada, said members of the Reformed churches are insistent that "one cannot know and love God without seeking justice," which in today's world means working for economic equality, women's rights and peace.

The Reformed churches, which have a combined total of about 80 million faithful, are not direct descendants of Martin Luther and the Protestant Reformation of 1517 -- the Waldensians were formed in the 12th century and many other members of the communion trace their founding to John Calvin. However, the World Communion of Reformed Churches adopted the 1999 Catholic-Lutheran statement on justification, an issue at the heart of Luther's protest and of key importance to Calvin. The 1999 agreement recognized that "by grace alone, in faith in Christ's saving work and not because of any merit on our part, we are accepted by God and receive the Holy Spirit, who renews our hearts while equipping and calling us to good works."

"On the basis of an agreement on the doctrine of justification," Pope Francis said, "there are many areas in which Reformed and Catholics can work together in bearing witness to God's merciful love, which is the true remedy for the confusion and indifference that seem to surround us."

Modern spiritual deserts seem to be growing, the pope told the group. "Especially in places where people live as if God did not exist, our Christian communities are meant to be sources of living water quenching thirst with hope, a presence capable of inspiring encounter, solidarity and love. They are called to receive and rekindle God's grace, to overcome self-centeredness and to be open to mission."

The answer, Pope Francis said, is for Christians to work together, promoting "a shared mission of evangelization and service."